<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>

    <style>
      html {
        font-size: 10px;
      }

      .container {
        display: flex;
        height: 40rem;
        background-color: aqua;
        /* flex-direction: column; */
        /* flex-wrap: wrap; */
        justify-content: center;
        align-items: center;
      }

      .item {
        width: 20rem;
        font-size: 8rem;
      }
    </style>
  </head>
  <body>
    <div class="container">
      <div class="item" style="background-color: red">1</div>
      <div class="item" style="background-color: orange">2</div>
      <div class="item" style="background-color: yellow">3</div>
      <div class="item" style="background-color: green">4</div>
      <div class="item" style="background-color: limegreen">5</div>
      <div class="item" style="background-color: blue">6</div>
    </div>
  </body>
</html>
